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Editorial Team
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Asked: 2026-06-15T03:08:42+00:00

static void RadioReleaseSPI(void) { __disable_interrupt(); spiTxRxByteCount &= ~0x0100; __enable_interrupt(); } I understand that multiple

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static void RadioReleaseSPI(void) {
    __disable_interrupt();
    spiTxRxByteCount &= ~0x0100;
    __enable_interrupt();
}

I understand that multiple tasks may attempt to use the SPI resource. spiTxRxByteCount is a global variable used to keep track of whether the SPI is currently in use by another task. When a task requires the SPI it can check the status of spiTxRxByteCount to see if the SPI is being used. When a task is done using the SPI it calls this function and clears the bit, to indicate that the SPI is now free. But why disable the interrupts first and then re-enable them after? Just paranoia?

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1 Answer

  1. Editorial Team

    The &= will do a read-modify-write operation – it’s not atomic. You don’t want an interrupt changing things in the middle of that, resulting in the write over-writing with an incorrect value.

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